System and method for providing link property types for content management

ABSTRACT

In accordance with embodiments, there are provided mechanisms and methods for providing linked property types in a content management system. These mechanisms and methods for providing linked property types in a content management system can enable users to specify a new property definition type, which refers to another node instance in the content management system. By specifying a link property definition type on a type, the user can then relate a node instance of the modeled type (link source) to any other node instance (link target) in the system. For example, a user can create a type Article with property definitions such as title, body and authorLink. The authorLink property definition can be a link type property definition. Then the user could define an Author content type. When an instance of an Article is created (anArticle), the authorLink property associated with anArticle could refer to a node instance of an Author.

CLAIM OF PRIORITY

This application claims the benefit of U.S. Provisional PatentApplication 60/720,860 entitled IMPROVED CONTENT MANAGEMENT, by RyanMcVeigh et al., filed Sep. 26, 2005, the entire contents of which areincorporated herein by reference.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

CROSS REFERENCE TO RELATED APPLICATIONS

The following commonly owned, co-pending United States Patents andPatent Applications, including the present application, are related toeach other. Each of the other patents/applications are incorporated byreference herein in its entirety:

U.S. patent application Ser. No. 11/438,202 entitled SYSTEM AND METHODFOR TYPE INHERITANCE FOR CONTENT MANAGEMENT, by Ryan McVeigh et al.,filed on May 22, 2006;

U.S. patent application Ser. No. 11/438,593 entitled SYSTEM AND METHODFOR PROVIDING NESTED TYPES FOR CONTENT MANAGEMENT, by Ryan McVeigh etal., filed on May 22, 2006; and

FIELD OF THE INVENTION

The current invention relates generally to managing content for use withportals and other content delivery mechanisms, and more particularly tomechanisms for type inheritance, abstract types, nested types and linkproperty types in a content management system.

BACKGROUND

Content repositories manage and provide access to large data stores suchas a newspaper archives, advertisements, inventories, image collections,etc. A content repository can be a key component of a web applicationsuch as a portal, which must quickly serve up different types of contentin response to user interaction. However, difficulties can arise whentrying to integrate more than one vendor's content repository. Each mayhave its own proprietary application program interface and contentservices (e.g., conventions for searching and manipulating content,versioning, workflows, and data formats). Furthermore, each time arepository is added to an application, the application software must bemodified to accommodate these differences. What is needed is a coherentsystem and method for interacting with disparate repositories and forproviding a uniform set of content services across all repositories,including those that lack such services.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary illustration of functional system layers invarious embodiments.

FIG. 2 is an exemplary illustration of objects/interfaces that can beused to interface repositories comprising content in variousembodiments.

FIGS. 3A-3C are operational flow diagrams illustrating a high leveloverview of techniques for type inheritance, nested types and linkproperty types in a content management system in embodiments.

FIGS. 4A-4B are data diagram illustrating database fields andrelationships supporting techniques for type inheritance, nested typesand link property types in embodiments.

FIG. 5 is a hardware block diagram of an example computer system, whichmay be used to embody one or more components in an embodiment.

DETAILED DESCRIPTION

The invention is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. References to embodiments in thisdisclosure are not necessarily to the same embodiment, and suchreferences mean at least one. While specific implementations arediscussed, it is understood that this is done for illustrative purposesonly. A person skilled in the relevant art will recognize that othercomponents and configurations may be used without departing from thescope and spirit of the invention.

In the following description, numerous specific details are set forth toprovide a thorough description of the invention. However, it will beapparent to those skilled in the art that the invention may be practicedwithout these specific details. In other instances, well-known featureshave not been described in detail so as not to obscure the invention.

Although a diagram may depict components as logically separate, suchdepiction is merely for illustrative purposes. It can be apparent tothose skilled in the art that the components portrayed can be combinedor divided into separate software, firmware and/or hardware components.For example, one or more of the embodiments described herein can beimplemented in a network accessible device/appliance such as a router.Furthermore, it can also be apparent to those skilled in the art thatsuch components, regardless of how they are combined or divided, canexecute on the same computing device or can be distributed amongdifferent computing devices connected by one or more networks or othersuitable communication means.

In accordance with embodiments, there are provided mechanisms andmethods for type inheritance in a content management system. Thesemechanisms and methods for type inheritance in a content managementsystem can enable users to create types that extend from another typerather than create from scratch. The ability of embodiments to providecreate types that extend from another type can enable a child type toautomatically inherit one or more property definitions as defined in aparent type. For example, a user can create a type clothing withproperty definitions such as color, size, etc. The user can then createanother type shirt, which “extends” the clothing type by adding a“sleeve length” property definition. Embodiments may further provide theability to have abstract types, nested types and link property types.

In an embodiment and by way of example, a method for type inheritance ina content management system is provided. One method embodiment includesreceiving a definition of a child data type, the child data type basedupon a parent data type. At least one node in a virtual contentrepository (VCR) can be determined from the definition of a child datatype. The node corresponds to the child data type and has at least onerelationship with at least one other node. The at least one relationshipcan support extension of at least one property by the child data typefrom the parent data type. The at least one other node corresponds tothe parent data type. The VCR models content in a plurality of contentrepositories. Content in the plurality of content repositories can thenbe managed based upon the VCR. In the event that either of the childdata type or the parent data types are abstract data types,instantiation of any nodes based upon the abstract data type is blocked.The notion of a type being inherited can be made transparent to contentnodes in embodiments.

In another aspect and according to embodiments, there are providedmechanisms and methods for providing nested variables in a contentmanagement system. These mechanisms and methods for providing nestedvariables in a content management system can enable users to model typesthat can be used within other type definitions. This differs from theType Inheritance feature in that types that make use of the nested typefeature do not extend their functionality but define a propertydefinition having a value defined by all property definitions in thenested type. For example, user can create a type address with propertydefinitions such as street, city, zip code, etc. The user can thencreate another type person that has property definitions such as “name”and home address and business address. The two address propertydefinitions can be represented by the address type, each with theaddress type's property definitions.

In an embodiment and by way of example, a method for providing nestedtypes in a content management system is provided. One method embodimentincludes receiving definitions of a first data type and a second datatype, the second data type based upon the first data type. At least onenode is determined from the definition of the second data type in avirtual content repository (VCR) that models content in a plurality ofcontent repositories. The at least one node corresponds to the seconddata type and has at least one relationship with at least one othernode. The at least one other node corresponds to the first data type.The at least one relationship corresponds to defining a property of thefirst data type having a value defined by property definitions in thesecond data type. Content in the plurality of content repositories canthen be managed based upon the VCR.

In a yet further aspect and according to embodiments, there are providedmechanisms and methods for providing linked property types in a contentmanagement system. These mechanisms and methods for providing linkedproperty types in a content management system can enable users tospecify a new property definition type, which refers to another nodeinstance in the content management system. By specifying a link propertydefinition type on a type, the user can then relate a node instance ofthe modeled type (link source) to any other node instance (link target)in the system. For example, a user can create a type Article withproperty definitions such as title, body and authorLink. The authorLinkproperty definition can be a link type property definition. Then theuser could define an Author content type. When an instance of an Articleis created (anArticle), the authorLink property associated withanArticle could refer to a node instance of an Author.

In an embodiment and by way of example, a method for providing linkedproperty types in a content management system is provided. One methodembodiment includes receiving a link property definition type comprisinga property definition type that refers to at least one node instance(“link target”) in the content management system. At least one node(“link source”) is determined from the definition of the link propertydefinition type in a virtual content repository (VCR) that modelscontent in a plurality of content repositories. The at least one nodecorresponds to the link property definition type and has at least onerelationship with the at least one node instance. The at least one nodeinstance corresponds to the link target. The at least one relationshipsupports relating the at least one node of the link source to the atleast one node instance of the link target. Content in the plurality ofcontent repositories can then be managed based upon the VCR.

As used herein, the term inheritance (or extension) is defined as whenan object extends or inherits from a parent object, it gains thefunctionality as described by that parent object. The object is alsocapable of modifying that functionality to suit the object's specificneeds. For content types, the functionality that can be extended and/ormodified is the parent type's property definitions. As used herein, theterm subtype is defined as a content type that has extended anothercontent type. This is typically the child in the parent-childrelationship. As used herein, the term Supertype (or Base Type) isdefined as a content type that has been extended by another contenttype. This is typically the parent in the parent-child relationship. Asused herein, the term overload is defined as the process by which a usermodifies a property definition specified by a supertype. As used herein,the term abstract type is defined as a type that cannot be“instantiated”. A user cannot create a node of an abstract type. Anabstract type may serve to be extended by other types (which could thenhave nodes instantiated) or a nested type within another type. As usedherein, the term container type is defined as a type that contains othertypes as part of its data model. As used herein, the term contained typeis defined as a type that is modeled within another type. This is doneby the container type creating a property definition of type “nestedtype” which refers to the type to be nested. As used herein, the termcontainer instance is defined as a node that is an instance of acontainer type. As used herein, the term contained instance is definedas a “node” that represents the property values of the nested propertytype within a container node. As used herein, the term link propertytype is defined as type of property definition that specifies a link toanother node in the content management system. As used herein, the termlink source is defined as the node containing the link property typeproperty. As used herein, the term link target is defined as the targetnode to which a link source node's link property refers. Multiple linksource nodes may reference the same target node. Further, link sourcescan target multiple link target nodes.

While the present invention is described with reference to an embodimentin which techniques for type inheritance, abstract types, nested typesand link property types in a content management system are implementedin an application server in conformance with the J2EE ManagementFramework using executable programs written in the Java™ programminglanguage, the present invention is not limited to the J2EE ManagementFramework nor the Java™ programming language. Embodiments may bepracticed using other interconnectivity specifications or programminglanguages, i.e., JSP and the like without departing from the scope ofthe embodiments claimed. (Java™ is a trademark of Sun Microsystems,Inc.).

FIG. 1 is an exemplary illustration of functional system layers invarious embodiments of the invention. Although this diagram depictscomponents as logically separate, such depiction is merely forillustrative purposes. It will be apparent to those skilled in the artthat the components portrayed in this figure can be arbitrarily combinedor divided into separate software, firmware and/or hardware.Furthermore, it will also be apparent to those skilled in the art thatsuch components, regardless of how they are combined or divided, canexecute on the same computing device or can be distributed amongdifferent computing devices connected by one or more networks or othersuitable communication means.

A content repository 112 represents a searchable data store. Suchsystems can relate structured content and unstructured content (e.g.,digitally scanned paper documents, Extensible Markup Language, PortableDocument Format, Hypertext Markup Language, electronic mail, images,video and audio streams, raw binary data, etc.) into a searchablecorpus. Content repositories can be coupled to or integrated withcontent management systems. Content management systems can provide forcontent workflow management, versioning, content review and approval,automatic content classification, event-driven content processing,process tracking and content delivery to other systems. By way ofillustration, if a user fills out a loan application on a web portal,the portal can forward the application to a content repository which, inturn, can contact a bank system, receive notification of loan approval,update the loan application in the repository and notify the user byrendering the approval information in a format appropriate for the webportal.

A virtual or federated content repository (hereinafter referred to as“VCR”) is a logical representation of one or more individual contentrepositories. For example, the VCR provides a single access point tomultiple repositories from the standpoint of application layer 120 butdoes not shield from the user that there is more than one repositoryavailable. The VCR can also add content services to repositories thatnatively lack them. Typically, the user interacts with the VCR byspecifying which repository an action is related to (such as adding anew node), or performing an action that applies to all repositories(such as searching for content). In various embodiments and by way ofillustration, this can be accomplished in part by use of an API(application program interface) 100 and an SPI (service providerinterface) 102. An API describes how entities in the application layercan interface with some program logic or functionality. The applicationlayer can include applications (and subdivisions thereof) that utilizethe API, such as processes, threads, servlets, portlets, objects,libraries, and other suitable application components. An SPI describeshow a service provider (e.g., a content repository, a content managementsystem) can be integrated into a system of some kind. The SPI isolatesdirect interaction with repositories from the API. In variousembodiments, this can be accomplished at run-time wherein the APIlibrary dynamically links to or loads the SPI library. In anotherembodiment, the SPI can be part of a server process such that the APIand the SPI can communicate over a network. The SPI can communicate withthe repositories using any number of means including, but not limitedto, shared memory, remote procedure calls and/or via one or moreintermediate server processes.

Content repositories may comprise a variety of interfaces for connectingwith the repository. For example, as shown in FIG. 1, a BEA formatrepository 113 a provided by BEA Systems, Inc. of San Jose, Calif., aDocumentum format repository 113 b, provided by EMC Corp. of Hopkinton,Mass., and a JSR-170 compliant repository 113 c may be integrated into aVCR and made accessible via a single federated API 100 by SPI 102.Individual SPI implementations 105 a, 105 b, 105 c provide formatspecific service provider interfaces to the BEA format repository 113 a,the Documentum format repository 113 b, and the JSR-170 formatrepository 113 c, respectively. It is noteworthy that not all of theformats illustrated in FIG. 1 will be present in all embodiments.Further, some embodiments will include other repository formats notillustrated by FIG. 1 for brevity.

API's and SPI's can be specified as a collection of classes/interfaces,data structures and/or methods/functions that work together to provide aprogrammatic means through which VCR service(s) can be accessed andutilized. By way of illustration, APIs and SPIs can be specified in anobject-oriented programming language, such as Java™ (available from SunMicrosystems, Inc. of Mountain View, Calif.) and C# (available fromMicrosoft Corp. of Redmond, Wash.). The API and SPI can be exposed in anumber of ways, including but not limited to static libraries, dynamiclink libraries, distributed objects, servers, class/interface instances,and other suitable means.

In various embodiments, the API presents a unified view of allrepositories to the application layer such that navigation, CRUDoperations (create, read, update, delete), versioning, workflows, andsearching operations initiated from the application layer operate on therepositories as though they were one. Repositories that implement theSPI can “plug into” the VCR. The SPI includes a set of interfaces andservices that support API functionality at the repository level. The APIand SPI share a content model that represents the combined content ofall repositories as a hierarchical namespace of nodes. Given a node N,nodes that are hierarchically inferior to N are referred to as childrenof N, whereas nodes that are hierarchically superior to N are referredto as parents of N. The top-most level of the hierarchy is termed thefederated root. There is no limit to the depth of the hierarchy. Invarious embodiments, repositories are children of the federated root.Each repository can itself have children.

By way of illustration, content mining facilities 104, processes/threads106, tag libraries 108, integrated development environments (IDEs) 110,and other libraries 118 can all utilize the API to interact with a VCR.An IDE can provide the ability for a user to interactively buildworkflows and/or content views. Content mining facilities can includeservices for automatically extracting content from the VCR based onparameters. Java ServerPages™ tag libraries enable portals to interactwith the VCR and surface its content on web pages. (Java ServerPages™ isavailable from Sun Microsystems, Inc.) In addition, it will be apparentto those of skill in the art that many other types of applications andsoftware components utilize the API and are, as such, fully within thescope and spirit of the present disclosure.

In various embodiments, the API can include optimizations to improve theperformance of interacting with the VCR. One or more caches 116 can beused to buffer search results and/or recently accessed nodes. Someimplementations may include additional cache 119 in one or morerepositories. In various embodiments, a cache can include a node cacheand/or a binary cache. A node cache can be used to provide fast accessto recently accessed nodes whereas a binary cache can be used to providefast access to the content/data associated with each node in a nodecache. The API can also provide a configuration facility 114 to enableapplications, tools and libraries to configure caches and the VCR. Invarious embodiments, this facility can be can be configured via JavaManagement Extension (JMX) (available from Sun Microsystems, Inc.).

In various embodiments, a model for representing hierarchy information,content and data types is shared between the API and the SPI. In thismodel, a node can represent hierarchy information, content or a schemainformation. Hierarchy nodes can serve as a containers for other nodesin the namespace akin to a file subdirectory in a hierarchical filesystem. Schema nodes represent predefined data types. Content nodesrepresent content/data. Nodes can have a shape defined by theirproperties. A property associates a name, a data type and an optional avalue that is appropriate for the type. In certain of these embodiments,the properties of content nodes contain values. By way of anillustration, a type can be any of the types described in Table 1. Thoseof skill in the art will appreciate that many more types are possibleand fully within the scope and spirit of the present disclosure.

TABLE 1 Exemplary Property Types in Various Embodiments PROPERTY TYPEDESCRIPTION Basic Text, a number, a date/time, a Boolean value, achoice, an image, a sound, a bit mask, an audio/visual presentation,binary data. Link A pointer/reference to data that lives “outside” of anode. Lookup An expression to be evaluated for locating another node inthe VCR Database Maps to an existing database table or view. Mapped (orschema) Nested One or more schemas define individual properties.

In various embodiments, a property can also indicate whether it isrequired, whether it is read-only, whether it provides a default value,and whether it specifies a property choice. A property choice indicatesif a property is a single unrestricted value, a single restricted value,a multiple unrestricted value, or a multiple restricted value.Properties that are single have only one value whereas properties thatare multiple can have more than one value. If a property is restricted,its value(s) are chosen from a finite set of values. But if a propertyis unrestricted, any value(s) can be provided for it. A property canalso be designated as a primary property. By way of illustration, theprimary property of a node can be considered its default content. Forexample, if a node contained a binary property to hold an image, itcould also contain a second binary property to represent a thumbnailview of the image. If the thumbnail view was the primary property,software applications such as browser could display it by default.

A named collection of one or more property types is a schema. A schemanode is a place holder for a schema. In various embodiments, schemas canbe used to specify a node's properties. By way of illustration, a Personschema with three properties (Name, Address and DateofBirth) can bedescribed for purposes of discussion as follows:

Schema Person = {   <Name=Name, Type=Text>,   <Name=Address,Type=Address>,   <Name=DateofBirth, Type=Date>}

Various embodiments allow a node to be defined based on a schema. By wayof illustration, a content node John can be given the same properties asthe schema Person:

Content Node John is a Person

In this case, the node John would have the following properties: Name,Address and DateofBirth. Alternatively, a node can use one or moreschemas to define individual properties. This is sometimes referred toas nested types. In the following illustration, John is defined havingan Info property that itself contains the properties Name, Address andDateofBirth. In addition, John also has a CustomerId property:

Content Node John = {   <Name=Info, Type=Person>,   <Name=CustomerId,Type=Number> }

Schemas can be defined logically in the VCR and/or in the individualrepositories that form the VCR. In certain embodiments, schemas caninherit properties from at least one other schema. Schema inheritancecan be unlimited in depth. That is, schema A can inherit from schema B,which itself can inherit from schema C, and so on. If several schemascontain repetitive properties, a “base” schema can be configured fromwhich the other schemas can inherit. For example, a Person schemacontaining the properties Name, Address and DateofBirth, can beinherited by an Employee schema which adds its own properties (i.e.,Employee ID, Date of Hire and Salary):

Schema Employee inherits from Person = {   <Name=EmployeeID, Type=Number>,   <Name=DateofHire, Type=Date>,   <Name=Salary, Type= Number> }

Thus, as defined above the Employee schema has the following properties:Name, Address, DateofBirth, EmployeeID, DateofHire and Salary. If thePerson schema had itself inherited properties from another schema, thoseproperties would also belong to Employee.

In various embodiments, nodes have names/identifiers and can bespecified programmatically or addressed using a path that designates thenode's location in a VCR namespace. By way of illustration, the path canspecify a path from the federated root (‘/’) to the node in question(‘c’):

/a/b/c

In this example, the opening ‘/’ represents the federated root, ‘a’represents a repository beneath the federated root, ‘b’ is a hierarchynode within the ‘a’ repository, and ‘c’ is the node in question. Thepath can also identify a property (“property1”) on a node:

/a/b/c.property1

In aspects of these embodiments, the path components occurring prior tothe node name can be omitted if the system can deduce the location ofthe node based on context information.

In various embodiments, a schema defined in one repository or the VCRcan inherit from one or more schemas defined in the same repository, adifferent repository or the VCR. In certain aspects of theseembodiments, if one or more of the repositories implicated by aninherited schema do not support inheritance, the inheriting schema canbe automatically defined in the VCR by the API. In one embodiment, theinheriting schema is defined in the VCR by default.

By way of illustration, the Employee schema located in the Avitechrepository inherits from the Person schema located beneath the Schemashierarchy node in the BEA repository:

Schema /Avitech/Employee inherits from /BEA/Schemas/Person = {  <Name=EmployeeID, Type= Number>,   <Name=DateofHire, Type=Date>,  <Name=Salary, Type= Number> }

In various embodiments, the link property type (see Table 1) allows forcontent reuse and the inclusion of content that may not be under controlof the VCR. By way of illustration, the value associated with a linkproperty can refer/point to any of the following: a content node in aVCR, an individual property on a content node in a VCR, a file on a filesystem, an object identified by a URL (Uniform Resource Locator), or anyother suitable identifier. In various embodiments, when editing acontent node that has a link property type, a user can specify the linkdestination (e.g., using a browser-type user interface). In certainaspects of these embodiments, if a link refers to a content node or acontent node property that has been moved, the link can be resolvedautomatically by the system to reflect the new location.

In various embodiments, a value whose type is lookup (see Table 1) canhold an expression that can be evaluated to search the VCR for instancesof content node(s) that satisfy the expression. Nodes that satisfy theexpression (if any) can be made available for subsequent processing. Invarious embodiments, a lookup expression can contain one or moreexpressions that can substitute expression variables from: the contentnode containing the lookup property, a user profile, anything in thescope of a request or a session. In various embodiments, an expressioncan include mathematical, logical and Boolean operators, function/methodinvocations, macros, SQL (Structured Query Language), and any othersuitable query language. In various embodiments, an expression can bepre-processed one or more times to perform variable substitution,constant folding and/or macro expansion. It will be apparent to those ofskill in the art that many other types of expressions are possible andfully within the scope and spirit of this disclosure.

In various embodiments, when editing a content node that has a lookupproperty type, the user can edit the expression through a user interfacethat allows the user to build the expression by either entering itdirectly and/or by selecting its constituent parts. In addition, theuser interface can enable the user to preview the results of theexpression evaluation.

Database mapped property types (see Table 1) allow information to beculled (i.e., mapped) from one or more database tables (or otherdatabase objects) and manipulated through node properties. By way ofillustration, a company might have “content” such as news articlesstored as rows in one or more RDBMS (Relational Database ManagementSystem) tables. The company might wish to make use of this “content” viatheir portal implementation. Further, they might wish to manage theinformation in this table as if it existed in the VCR. Onceinstantiated, a content node property that is of the database mappedtype behaves as though its content is in the VCR (rather than thedatabase table). In one embodiment, all API operations on the propertybehave the same but ultimately operate on the information in thedatabase table.

In various embodiments, a given database mapped property type can havean expression (e.g., SQL) which, when evaluated, resolves to a row and acolumn in a database table (or resolves to any kind of database object)accessible by the system over one or more networks. A database mappedproperty will be able to use either native database tables/objects ordatabase views on those tables/objects. It will be appreciated by thoseof skill in the art that the present disclosure is not limited to anyparticular type of database or resolving expression.

In aspects of certain embodiments, a schema can be automatically createdthat maps to any row in a database table. The system can inspect thedata structure of the table and pre-populate the schema with databasemapped properties corresponding to columns from the table. The tablecolumn names can be used as the default property names and likewise thedata type of each column will determine the data type of eachcorresponding property. The system can also indicate in the schema,which properties correspond to primary key columns. If certain columnsfrom the table are not to be used in the new schema, they can beun-mapped (i.e. deselected) by a user or a process. A content node canbe based on such a schema and can be automatically bound to a row in adatabase table (or other database object) when it is instantiated. Invarious embodiments, a user can interactively specify the databaseobject by browsing the database table.

While not required by all embodiments, some embodiments employ a displaytemplate (or “template”) to display content based on a schema. Templatescan implement various “views”. By way of illustration, views could be“full”, “thumbnail”, and “list” but additional “views” could be definedby end-users. A full view can be the largest, or full page view of thecontent. A thumbnail view would be a very small view and a list view canbe used when displaying multiple content nodes as a “list” on the page(e.g., a product catalog search results page). In various embodiments,the association between a schema and templates can be one-to-many. Atemplate can be designated as the default template for a schema. Incertain of these embodiments, templates can be designed with the aid ofan integrated development environment (IDE). Other delivery mechanismssuch as without limitation mobile phones, XML, and the like can beenabled by this technology.

In various embodiments and by way of illustration, display templates canbe implemented using HTML (Hypertext Markup Language) and JSP (Java®Server Pages). By way of a further illustration, such a display templatecan be accessed from a web page through a JSP tag that can accept as anargument the identifier of a content node. Given the content node, thenode's schema and associated default display template can be derived andrendered. Alternatively, the JSP tag can take an additional argument tospecify a view other than the default. In another embodiment, displaytemplates can be automatically generated (e.g., beforehand ordynamically at run-time) based on a content node's schema. In otherembodiments, the view (e.g., full, thumbnail, list) can be determinedautomatically based on the contents of an HTTP request.

In various embodiments, a role is a dynamic set of users. By way ofillustration, a role can be based on functional responsibilities sharedby its members. In aspects of these embodiments, a role can be definedby one or more membership criteria. Role mapping is the process by whichit is determined whether or not a user satisfies the membership criteriafor a given role. For purposes of discussion, a role can be described asfollows:Role=PMembers+[Membership Criterial]

where PMembers is a set of user(s), group(s) and/or other role(s) thatform a pool of potential members of this role subject to the MembershipCriteria, if any. A user or a process can be in a role, if that user orprocess belongs to PMembers or satisfies the Membership Criteria. It isnoteworthy that a user or process does not need to be a member ofPMembers to be considered a member of the role. For example, it ispossible to define a role with a criterion such as: “Only on Thursdays”as its membership criteria. All users would qualify as a member of thisrole on Thursdays. The Membership Criteria can include one or moreconditions. By way of illustration, such conditions can include, but arenot limited to, one or more (possibly nested and intermixed) Boolean,mathematical, functional, relational, and/or logical expressions. By wayof illustration, consider the following Administrator role:Administrator=Joe, Mary, SuperUser+CurrentTime>5:00 pm

The role has as its potential members two users (Joe and Mary) and usersbelonging to the user group named SuperUser. The membership criteriaincludes a condition that requires the current time to be after 5:00 pm.Thus, if a user is Joe, Marry or belongs to the SuperUser group, and thecurrent time is after 5:00 pm, the user is a member of the Administratorrole.

In various embodiments, roles can be associated with Resource(s). By wayof illustration, a resource can be any system and/or application asset(e.g., VCR nodes and node properties, VCR schemas and schema properties,operating system resources, virtual machine resources, J2EE applicationresources, and any other entity that can be used by or be a part ofsoftware/firmware of some kind). Typically, resources can be arranged inone or more hierarchies such that parent/child relationships areestablished (e.g., the VCR hierarchical namespace and the schemainheritance hierarchy). In certain of these embodiments, a containmentmodel for roles is followed that enables child resources to inheritroles associated with their parents. In addition, child resources canoverride their parents' roles with roles of their own.

In various embodiments, Membership Criteria can be based at leastpartially on a node's properties. This allows for roles that can compareinformation about a user/process to content in the VCR, for example. Invarious embodiments, a node's property can be programmatically accessedusing dot notation: Article.Creator is the Creator property of theArticle node. By way of illustration, assume an Article node thatrepresents a news article and includes two properties: Creator andState. A system can automatically set the Creator property to the nameof the user that created the article. The State property indicates thecurrent status of the article from a publication workflow standpoint(e.g., whether the article is a draft or has been approved forpublication). In this example, two roles are defined (see Table 2).

TABLE 2 Exemplary Roles in an Embodiment ROLE ASSOCIATED MEMBERSHIP NAMEWITH PMEMBERS CRITERIA Submitter Article Article.Creator Article.State =Draft Approver Article Editor Article.State = (Submitted or Approved)

The Submitter and Approver roles are associated with the Article node.Content nodes instantiated from this schema will inherit these roles. Ifa user attempting to access the article is the article's creator and thearticle's state is Draft, the user can be in the Submitter role.Likewise, if a user belongs to an Editor group and the article's stateis Submitted or Approved, then the user can belong to the Approver role.

In various embodiments, a policy can be used to determine whatcapabilities or privileges for a given resource are made available tothe policy's Subjects (e.g., user(s), group(s) and/or role(s)). Forpurposes of discussion, a policy can be described as follows:Policy=Resource+Privilege(s)+Subjects+[Policy Criteria]

Policy mapping is the process by which Policy Criteria, if any, areevaluated to determine which Subjects are granted access to one or morePrivileges on a Resource. Policy Criteria can include one or moreconditions. By way of illustration, such conditions can include, but arenot limited to, one or more (possibly nested and intermixed) Boolean,mathematical, functional, relational, and/or logical expressions.Aspects of certain embodiments allow policy mapping to occur just priorto when an access decision is rendered for a resource.

Similar to roles, in certain of these embodiments a containment modelfor policies is followed that enables child resources to inheritpolicies associated with their parents. In addition, child resources canoverride their parents' polices with policies of their own.

In various embodiments, policies on nodes can control access toprivileges associated with the nodes. By way of illustration, given thefollowing policies:

Policy1 = Printer504 + Read/View + Marketing   Policy2 = Printer504 +All + Engineeringthe Marketing role can read/view and browse the Printer504 resourcewhereas the Engineering role has full access to it (“All”). Theseprivileges are summarized in Table 3. Policy1 allows a user in theMarketing role to merely view the properties of Printer504 whereasPolicy2 allows a user in the Engineering role to view and modify itsproperties, to create content nodes based on Printer504 (assuming it isa schema), and to delete the resource.

TABLE 3 Exemplary Privileges for a “Printer504” Node in VariousEmbodiments READ/ ROLE CREATE VIEW UPDATE DELETE BROWSE Marketing x xEngineering x x x x x

Aspects of certain of these embodiments include an implied hierarchy forprivileges wherein child privilege(s) of a parent privilege areautomatically granted if the parent privilege is granted by a policy.

In various embodiments, the containment models for polices and roles areextended to allow the properties of a node to inherit the policies androles that are incident on the node. Roles/polices on properties canalso override inherited roles/polices. For purposes of illustration,assume the following policy on a Power property of Printer504:Policy3=Printer504.Power+Update+Marketing

In Policy3, the Marketing role is granted the right to update the Powerproperty for the printer resource Printer504 (e.g., control whether theprinter is turned on or off). By default, the Read/View property is alsogranted according to an implied privilege hierarchy. (There is no Browseprivilege for this property.) See Table 4. Alternatively, if there wasno implied privilege hierarchy, the Power property would inherit theread/view privilege for the Marketing role from its parent, Printer504.Although no policy was specified for the Power property and theEngineering role, the privileges accorded to the Engineering role can beinherited from a parent node. These privileges are summarized in Table4.

TABLE 4 Exemplary Privileges for the “Power” Property in the“Printer504” Node ROLE CREATE READ/VIEW UPDATE DELETE Marketing x xEngineering X x x x

In various embodiments, the ability to instantiate a node based on aschema can be privileged. This can be used to control which types ofcontent can be created by a user or a process. By way of illustration,assume the following policy:Policy4=Press_Release+Instantiate+Marketing, Manager

Policy4 specifies that nodes created based on the schema Press_Releasecan only be instantiated by users/processes who are members of theMarketing and/or Manager roles. In aspects of certain of theseembodiments, user interfaces can use knowledge of these policies torestrict available user choices (e.g., users should only be able to seeand choose schemas on which they have the Instantiate privilege).

In various embodiments, policies can be placed on schemas. For purposesof illustration, assume the following policies:

Policy5 = Press_Release + Read/View + Everyone Policy6 = Press_Release +All + Public_Relations

TABLE 5 Exemplary Privileges for the “Press Release” Schema CREATE READ/ROLE INSTANCE VIEW UPDATE DELETE BROWSE Everyone X x Public x X x x xRelations

With reference to Table 5 and by way of illustration, assume a contentnode instance was created based on the Press Release schema. By default,it would have the same roles/polices as the Press Release schema. If apolicy was added to the node giving a role “Editor” the privilege toupdate the node, the result would be additive. That is, Everyone andPublic Relations would maintain their original privileges.

In various embodiments, policies can be placed on properties within aschema, including property choices. (Property choices are apredetermined set of allowable values for a given property. For example,a “colors” property could have the property choices “red”, “green” and“blue”.)

FIG. 2 is an exemplary illustration of objects/interfaces that can beused to interface repositories comprising content in variousembodiments. Although this diagram depicts components as logicallyseparate, such depiction is merely for illustrative purposes. It will beapparent to those skilled in the art that the components portrayed inthis figure can be arbitrarily combined or divided into separatesoftware, firmware and/or hardware. Furthermore, it will also beapparent to those skilled in the art that such components, regardless ofhow they are combined or divided, can execute on the same computingdevice or can be distributed among different computing devices connectedby one or more networks or other suitable communication means.

The ContentManagerFactory 202 can serve as a representation of an accessdevice from an application program's 200 point of view. In aspects ofthese embodiments, the ContentManagerFactory attempts to connect allavailable repositories to the device (e.g., 212-216); optionally withuser or process credentials. In various embodiments, this can be basedon the Java™ Authentication and Authorization Service (available fromSun Microsystems, Inc.). Those of skill in the art will recognize thatmany authorization schemes are possible without departing from the scopeand spirit of the present disclosure. Each available content repositoryis represented by an SPI Repository object 206-210. In an embodiment,the ContentManagerFactory can invoke a connect( ) method on the set ofRepository objects. Alternatively, in some embodiments, the notion of“connecting” to a repository is not exposed to users. In variousembodiments, the ContentManagerFactory returns a list of repositorysession objects to the application program, one for each repository forwhich a connection was attempted. Any error in the connection procedurecan be described by the session object's state. In another embodiment,the ContentManagerFactory can connect to a specific repository given therepository name. In various embodiments, the name of a repository can bea URI (uniform resource identifier).

Type Inheritance

FIG. 3A is an operational flow diagram illustrating a high leveloverview of a technique for type inheritance in a content managementsystem in an embodiment. As shown in FIG. 3A, a definition of a childdata type is received (block 302). The child data type can be based upona parent data type. One or more nodes in a virtual content repository(VCR) may be determined from the definition of the child data type(block 304). The node(s) correspond to the child data type and have atleast one relationship with at least one other node. At least one othernode corresponds to the parent data type. The at least one relationshipsupports extension of at least one property from the parent data type.The VCR models content in a plurality of content repositories. Contentin the plurality of content repositories is managed (block 306) basedupon the VCR.

In some embodiments, type Inheritance is limited to within the contextof a single repository. In some embodiments, a static inheritance modelis enforced. In other words, nodes of a type will have the sameproperties. In some embodiments, a singular model having unlimited depthis enforced. In other words, the inheritance model supports chain types:a->b->c-> . . . ->z and so on. In some embodiments, a given type isrestricted to inheriting from a single parent. In some embodiments,cyclical inheritance chains are blocked. In other words, an inheritancechain such as A->B->A cannot be formed. In some embodiments, an attemptto create a property definition by the child type with the same name asa parent type is blocked. In some embodiments, a child type is enabledto overload a given property definition. In some embodiments, retrievalof a node of a subtype does not require knowledge of the type'sstructure. Rather, this can be obtained by interrogating the typeobject. In some embodiments, when a user requests all nodes of a giventype, nodes of the specified type and those of types that extend thespecified type are returned. In some embodiments, nodes are preventedfrom being “downcast”. In other words, if a user has an instance of asubtype, the node will behave like the subtype, not as an instance ofthe parent type. In some embodiments, the nodes are blocked fromdetermining which properties are inherited from other types from whichthe nodes were instantiated. This can make the inheritance concept istransparent to nodes. Some embodiments support type security for eachtype and/or versioning of nodes.

The following scenario illustrate operation of an embodiment providingabstract data types:

-   -   A user creates a type and at creation time indicates that the        type is abstract. The abstract modifier is simply a boolean        flag.    -   The user then attempts to create a node from the abstract type.        This operation should fail with indication that an instance of        an abstract type is illegal.

The following scenario illustrate operation of an embodiment providingabstract data type updating:

-   -   A user creates an abstract type.    -   The user updates the type to disable the abstract modifier.    -   The user is then able to create instances of this type.

The following scenario illustrates operation of an embodiment providingdetection that an abstract data type is not abstract:

-   -   A user creates a type—not specifying the abstract modifier. By        default behavior the type is not abstract.    -   The user creates an instance of this type.    -   The user attempts to make the type abstract, with instances of        the type in existence. This operation fails with indication that        a type cannot be made abstract while it has instances.    -   All instances of the type are then removed.    -   The type can then be modified to become abstract.

The following scenario illustrates operation of an embodiment providingabstract data type removal:

-   -   A user creates an abstract type.    -   The user is free to remove this type at any time unless it is a        supertype (and therefore engaged in type inheritance) or it is a        nested type within another type. When the inheritance        relationship is broken and the abstract type is no longer a        supertype to another type, then it may be freely removed.

The following scenario illustrates operation of an embodiment providingabstract data type inheritance:

-   -   A user creates an abstract type.    -   The type may be used as a base type for inheritance. No behavior        is implied by the selection of an abstract type as a base type.        The abstract type's behavior does not change in being used as a        base type, aside from the fact that it cannot be removed if a        subtype has any instances.

FIGS. 4A-4B are data diagrams illustrating database fields andrelationships supporting inheritance of types, nested types and linkproperty types in an embodiment. In FIG. 4A, IS_ABSTRACT (BOOLEAN),PARENT_OBJECT_CLASS_ID (LONG, NULL) and PATH (VARCHAR, NULL) columns areadded to a CM_OBJECT_CLASS. A PROPERTY_DEFINITION_TYPE (INT) is added toa CM_PROPERTY_DEFINITION.

Nested Types

FIG. 3B is an operational flow diagram illustrating a high leveloverview of a technique for nested types in a content management systemin an embodiment. As shown in FIG. 3B, definitions of a first data typeand a second data type are received (block 312). The second data typebased upon the first data type. At least one node is determined (block314) from the definition of the second data type in a virtual contentrepository (VCR) that models content in a plurality of contentrepositories. The at least one node corresponds to the second data typeand has at least one relationship with at least one other node. The atleast one other node corresponds to the first data type. The at leastone relationship corresponds to defining a property of the first datatype having a value defined by property definitions in the second datatype. Content in the plurality of content repositories is managed (block316) based upon the VCR.

In some embodiments, nesting is limited to within the context of asingle repository. In some embodiments, a model having unlimited depthis enforced. In other words, a user could model a type that nestsanother type that nests another type and so on. In some embodiments,cyclical nesting chains are blocked. In other words, a user is notallowed to model a “type A” which contains “type B” which contains “typeC” which in turn contains “type A”.

In some embodiments, nested instances are treated as “contained” nodesfor the purpose of exposure in the API. In other words, embodimentsreturn a node or some other structure that represents the set ofproperty values that make up the “contained node” when a user invokes amethod for a property that returns a nested type.

In some embodiments, properties may be updated by building the nestedhierarchy. In some embodiments, nested instances are managed explicitlyby their containing instances. There is no representation to the userthat a nested instance exists outside of the containing instance. Insome embodiments, a nested type and/or a container type cam be abstracttypes. In some embodiments, it is possible to have more than oneinstance of the nested type, i.e., the type is multivalued.

In some embodiments, any type can have a primary property definitiondefined. If that type gets nested within another type, the primaryproperty definition has no affect on the container type. The containertype is limited to understanding a primary property definition definedfor that particular type, but not for any of the nested types. A nestedtype in a container type can have one or more of the following primaryproperty definitions:

-   -   Property Name—Property definitions of container and nested types        don't interrelate and therefore no restriction on their names        apply. It is perfectly legal to have a “name” property        definition in both a container type and within a type the        container nests.    -   Property Type—Represented as a nested property type.    -   Mandatory—Allowed.    -   Read Only—Not allowed (though property definitions w/in the        nested type can be read only).    -   Restricted—Not allowed. When a user selects the “nested type”        for a property definition, they may not specify a property        choice (and therefore a default value) for the nested instance.    -   Multi Valued—More than one instance of the nested type        permitted.    -   Column Name—Not allowed.

A container type can have the following property definitions for CRUDoperations:

-   -   For the container type property definition (that represents the        nested type, i.e. homeAddress), all CRUD actions are allowable        except for column name or restriction (which make no sense to        have defined for a nested type).    -   For the nested type property definitions—the same update and        delete rules apply as for property definitions that haven't been        nested, except the presence of the instances/nodes for the        nested and container types is checked.

In some embodiments, a containing type property returns the nested typeinstance as a Property with a Value of java type Property [ ], callednestedValue. Specifically, when a property is obtained from a node thatrepresents a nested type (i.e., homeAddress), a Property with a Valuethat has been instantiated as a Property[ ] containing all of the valuesfor each property defined in the address type, will be returned.

In some embodiments, type level security and node level security areprovided. In type level security, READ capability of the nested type isrequired to create the containment association. Further, a user withoutREAD capability on a nested type cannot read the container type. In nodelevel security, CCI of container and all nested types is required.

In some embodiments, nested types can be searched. For example, a searchfor City=“Boulder” returns all nodes with a PD name of “City” with avalue of “Boulder”, regardless of type.

In some embodiments, nested types can interact with other type features.For example:

-   -   Polymoprhism of nested types is disallowed.    -   Types may be nested at any level (parent, child, etc)    -   Any nested type may be inherited

The following scenario illustrate operation of an embodiment providingabstract type nested:

-   -   A user creates an abstract type.    -   The type may be used as a nested type. No behavior is implied by        the selection of an abstract type as a nested type. The abstract        type's behavior does not change in being used as a nested type,        aside from the fact that it cannot be removed if a container        type has any instances.

FIGS. 4A-4B are data diagrams illustrating database fields andrelationships supporting inheritance of types, nested types and linkproperty types in an embodiment. In FIG. 4A, a columnNESTED_OBJECT_CLASS_ID (of type NUMBER, to be a FK to CM_OBJECT_CLASS)is added to the CM_PROPERTY_DEFINITION table. The PROPERTY_NAME in theCM_PROPERTY table is altered to be about 900 chars wide and a columnNESTED_GROUP_ID (of type VARCHAR(254) null) is added. In FIG. 4B, thePROPERTY_NAME in the CMV_PROPERTY table is altered to be about 900 charswide.

Link Property Types

FIG. 3C is an operational flow diagram illustrating a high leveloverview of a technique for link property types in a content managementsystem in an embodiment. As shown in FIG. 3C, a link property definitiontype comprising a property definition type that refers to at least onenode instance (“link target”) in the content management system isreceived (block 322). At least one node (“link source”) is determinedfrom the definition of the link property definition type in a virtualcontent repository (VCR) that models content in a plurality of contentrepositories (block 324). The at least one node corresponds to the linkproperty definition type and has at least one relationship with the atleast one node instance. The at least one node instance corresponds tothe link target. The at least one relationship supports relating the atleast one node of the link source to the at least one node instance ofthe link target. Content in the plurality of content repositories ismanaged (block 326) based upon the VCR. It is noteworthy that linksources can target multiple link target nodes.

In some embodiments, a link target can refer to any node in therepository regardless of ObjectClass type, or whether or not it is acontent or hierarchy node. In some embodiments, there is no limit to thenumber of link property definitions that can be placed on a given type.In some embodiments, a link property definition type will not permit thecreation of property choices and therefore default values for theproperty.

In some embodiments, when a method to retrieve a property is invoked onthe node to retrieve the link property value, the following processingwill occur:

-   -   If the target node exists, the target node will be retrieved.    -   If the target node has not yet been specified, the getProperty(        ) method will return null.    -   If the target node has been specified, but does not exist, an        exception type that extends RepositoryException will be thrown.

In some embodiments, a node which other nodes have as a link propertytarget can be deleted. In some embodiments, existence of a link propertytarget node is verified when a method for setting a property is invoked.In some embodiments, if the link target node is not null and the nodedoes not exist, an exception will be thrown. In some embodiments, anode's properties may be versioned, but versioning is not performed onany nodes to which a link property refers. In some embodiments, linkedproperty types cannot be used in search.

FIGS. 4A-4B are data diagrams illustrating database fields andrelationships supporting inheritance of types, nested types and linkproperty types in an embodiment. In FIG. 4A, a LINKED_NODE_UID column(FK to CM_NODE) is added to CM_PROPERTY. In FIG. 4B, a LINKED_NODE_UIDcolumn (FK to CM_NODE) is added to CMV_VALUE.

In other aspects, the invention encompasses in some embodiments,computer apparatus, computing systems and machine-readable mediaconfigured to carry out the foregoing methods. In addition to anembodiment consisting of specifically designed integrated circuits orother electronics, the present invention may be conveniently implementedusing a conventional general purpose or a specialized digital computeror microprocessor programmed according to the teachings of the presentdisclosure, as will be apparent to those skilled in the computer art.

Appropriate software coding can readily be prepared by skilledprogrammers based on the teachings of the present disclosure, as will beapparent to those skilled in the software art. The invention may also beimplemented by the preparation of application specific integratedcircuits or by interconnecting an appropriate network of conventionalcomponent circuits, as will be readily apparent to those skilled in theart.

The present invention includes a computer program product which is astorage medium (media) having instructions stored thereon/in which canbe used to program a computer to perform any of the processes of thepresent invention. The storage medium can include, but is not limitedto, any type of rotating media including floppy disks, optical discs,DVD, CD-ROMs, microdrive, and magneto-optical disks, and magnetic oroptical cards, nanosystems (including molecular memory ICs), or any typeof media or device suitable for storing instructions and/or data.

Stored on any one of the machine readable medium (media), the presentinvention includes software for controlling both the hardware of thegeneral purpose/specialized computer or microprocessor, and for enablingthe computer or microprocessor to interact with a human user or othermechanism utilizing the results of the present invention. Such softwaremay include, but is not limited to, device drivers, operating systems,and user applications.

Included in the programming (software) of the general/specializedcomputer or microprocessor are software modules for implementing theteachings of the present invention, including, but not limited toproviding mechanisms and methods for type inheritance, nested types andlink property types in a content management system as discussed herein.

FIG. 5 illustrates an exemplary processing system 500, which cancomprise one or more of the elements of FIG. 1. Turning now to FIG. 5,an exemplary computing system is illustrated that may comprise one ormore of the components of FIG. 1. While other alternatives might beutilized, it will be presumed for clarity sake that components of thesystems of FIG. 1 are implemented in hardware, software or somecombination by one or more computing systems consistent therewith,unless otherwise indicated.

Computing system 500 comprises components coupled via one or morecommunication channels (e.g., bus 501) including one or more general orspecial purpose processors 502, such as a Pentium®, Centrino®, PowerPC®, digital signal processor (“DSP”), and so on. System 500 componentsalso include one or more input devices 503 (such as a mouse, keyboard,microphone, pen, and so on), and one or more output devices 504, such asa suitable display, speakers, actuators, and so on, in accordance with aparticular application. (It will be appreciated that input or outputdevices can also similarly include more specialized devices orhardware/software device enhancements suitable for use by the mentallyor physically challenged.)

System 500 also includes a machine readable storage media reader 505coupled to a machine readable storage medium 506, such as astorage/memory device or hard or removable storage/memory media; suchdevices or media are further indicated separately as storage 508 andmemory 509, which may include hard disk variants, floppy/compact diskvariants, digital versatile disk (“DVD”) variants, smart cards, readonly memory, random access memory, cache memory, and so on, inaccordance with the requirements of a particular application. One ormore suitable communication interfaces 507 may also be included, such asa modem, DSL, infrared, RF or other suitable transceiver, and so on forproviding inter-device communication directly or via one or moresuitable private or public networks or other components that may includebut are not limited to those already discussed.

Working memory 510 further includes operating system (“OS”) 511 elementsand other programs 512, such as one or more of application programs,mobile code, data, and so on for implementing system 500 components thatmight be stored or loaded therein during use. The particular OS or OSsmay vary in accordance with a particular device, features or otheraspects in accordance with a particular application (e.g. Windows®,WindowsCE™, Mac™, Linux, Unix or Palm™ OS variants, a cell phone OS, aproprietary OS, Symbian™, and so on). Various programming languages orother tools can also be utilized, such as those compatible with Cvariants (e.g., C++, C#), the Java™ 2 Platform, Enterprise Edition(“J2EE”) or other programming languages in accordance with therequirements of a particular application. Other programs 512 mayfurther, for example, include one or more of activity systems, educationmanagers, education integrators, or interface, security, othersynchronization, other browser or groupware code, and so on, includingbut not limited to those discussed elsewhere herein.

When implemented in software (e.g. as an application program, object,agent, downloadable, servlet, and so on in whole or part), a learningintegration system or other component may be communicated transitionallyor more persistently from local or remote storage to memory (SRAM, cachememory, etc.) for execution, or another suitable mechanism can beutilized, and components may be implemented in compiled or interpretiveform. Input, intermediate or resulting data or functional elements mayfurther reside more transitionally or more persistently in a storagemedia, cache or other volatile or non-volatile memory, (e.g., or memory509) in accordance with a particular application.

Other features, aspects and objects of the invention can be obtainedfrom a review of the figures and the claims. It is to be understood thatother embodiments of the invention can be developed and fall within thespirit and scope of the invention and claims. The foregoing descriptionof preferred embodiments of the present invention has been provided forthe purposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise forms disclosed.Many modifications and variations will be apparent to the practitionerskilled in the art. The embodiments were chosen and described in orderto best explain the principles of the invention and its practicalapplication, thereby enabling others skilled in the art to understandthe invention for various embodiments and with various modificationsthat are suited to the particular use contemplated. It is intended thatthe scope of the invention be defined by the following claims and theirequivalence.

1. A method for providing a link property definition type mechanism in acontent management system, the method comprising: providing a virtualcontent repository (VCR) with a plurality of content repositories;associating the VCR with an application programming interface (API),wherein a user of the VCR uses the API to manipulate content in theplurality of content repositories in a programming language; modelingcontent in the plurality of content repositories using a general serviceprovider interface (SPI), wherein the general SPI isolates directinteraction with each content repository in the plurality of contentrepositories from the API; associating a plurality of format specificcontent repositories with the general SPI, wherein each format specificcontent repository is associated with the general SPI through a formatspecific SPI implementation, and wherein each format specific SPIimplementation connects indirectly with the API through the general SPIand provides a different format specific SPI for a different formatspecific content repository; providing a link property definition typethat relates a plurality of source nodes to a plurality of target nodes,wherein one source node of the plurality of source nodes is a first nodewithin a first content repository in the VCR, and one target node of theplurality of target nodes is a second node in a second contentrepository in the VCR, wherein one of the first content repository andthe second content repository uses a format specific SPI that isdifferent from the general SPI; instantiating a software object type inthe programming language using the API, wherein the software object typeis associated with the link property definition type; accessing, via aninstance of the software object type and the API, said target node fromsaid source node through both the general SPI and the format specificSPI, based on the definition of the link property definition type; andmanaging content in the plurality of content repositories based upon theVCR.
 2. The method of claim 1, further comprising: receiving aspecification of the link property definition type.
 3. The method ofclaim 1, further comprising: blocking creation of property choices forthe link property definition type.
 4. The method of claim 3, furthercomprising: blocking specifying default values for a property.
 5. Themethod of claim 1, further comprising: retrieving a property of thefirst node by at least one of: retrieving a target node when the targetnode exists, wherein the target node is a node in the second contentrepository; returning null when a target node has not yet beenspecified; and raising an exception.
 6. The method of claim 1, furthercomprising: permitting a node which other nodes have as a link propertytarget to be deleted.
 7. The method of claim 1, further comprising:relating the first node to another target node of the plurality oftarget nodes during operations on the VCR.
 8. The method of claim 1,further comprising: associating the general SPI with a general SPIlibrary, and the general SPI library is at least one of linked to andloaded in at run-time by an API library that is associated with the API.9. A machine-readable storage medium carrying one or more sequences ofinstructions for providing a link property definition type mechanism ina content management system, which instructions, when executed by one ormore processors, cause the one or more processors to carry out the stepsof: providing a virtual content repository (VCR) with a plurality ofcontent repositories; associating the VCR with an applicationprogramming interface (API), wherein a user of the VCR uses the API tomanipulate content in the plurality of content repositories in aprogramming language; modeling content in the plurality of contentrepositories using a general service provider interface (SPI), whereinthe general SPI isolates direct interaction with each content repositoryin the plurality of content repositories from the API; associating aplurality of format specific content repositories with the general SPI,wherein each format specific content repository is associated with thegeneral SPI through a format specific SPI implementation, and whereineach format specific SPI implementation connects indirectly with the APIthrough the general SPI and provides a different format specific SPI fora different format specific content repository; providing a linkproperty definition type that relates a plurality of source nodes to aplurality of target nodes, wherein one source node of the plurality ofsource nodes is a first node within a first content repository in theVCR, and one target node of the plurality of target nodes is a secondnode in a second content repository in the VCR, wherein one of the firstcontent repository and the second content repository uses a formatspecific SPI that is different from the general SPI; instantiating asoftware object type in the programming language using the API, whereinthe software object type is associated with the link property definitiontype; accessing, via an instance of the software object type and theAPI, said target node from said source node through both the general SPIand the format specific SPI, based on the definition of the linkproperty definition type; and managing content in the plurality ofcontent repositories based upon the VCR.
 10. The machine-readablestorage medium as recited in claim 9, further include instructions forcarrying out the step of: receiving a specification of the link propertydefinition type.
 11. The machine-readable storage medium as recited inclaim 9, further include instructions for carrying out the step of:blocking creation of property choices for the link property definitiontype.
 12. The machine-readable storage medium as recited in claim 11,wherein the instructions for carrying out the step of blocking creationof property choices for a link property definition type includeinstructions for carrying out the step of: blocking specifying defaultvalues for a property.
 13. The machine-readable storage medium asrecited in claim 9, further include instructions for carrying out thestep of: retrieving a property of the first node by at least one of:retrieving a target node when the target node exists, wherein the targetnode is a node in the second content repository; returning null when atarget node has not yet been specified; and raising an exception. 14.The machine-readable storage medium as recited in claim 9, furtherinclude instructions for carrying out the step of: permitting a nodewhich other nodes have as a link property target to be deleted.
 15. Themachine-readable storage medium as recited in claim 9, wherein theinstructions for carrying out the step of managing content in theplurality of content repositories based upon the VCR includeinstructions for carrying out the step of: relating the first node toanother target node of the plurality of target nodes during operationson the VCR.
 16. An apparatus for providing a link property definitiontype mechanism in a content management system, the apparatus comprising:a processor; and one or more stored sequences of instructions which,when executed by the processor, cause the processor to carry out thesteps of: providing a virtual content repository (VCR) with a pluralityof content repositories; associating the VCR with an applicationprogramming interface (API), wherein a user of the VCR uses the API tomanipulate content in the plurality of content repositories in aprogramming language; modeling content in the plurality of contentrepositories using a general service provider interface (SPI), whereinthe general SPI isolates direct interaction with each content repositoryin the plurality of content repositories from the API; associating aplurality of format specific content repositories with the general SPI,wherein each format specific content repository is associated with thegeneral SPI through a format specific SPI implementation, and whereineach format specific SPI implementation connects indirectly with the APIthrough the general SPI and provides a different format specific SPI fora different format specific content repository; providing a linkproperty definition type that relates a plurality of source nodes to aplurality of target nodes, wherein one source node of the plurality ofsource nodes is a first node within a first content repository in theVCR, and one target node of the plurality of target nodes is a secondnode in a second content repository in the VCR, wherein one of the firstcontent repository and the second content repository uses a formatspecific SPI that is different from the general SPI; instantiating asoftware object type in the programming language using the API, whereinthe software object type is associated with the link property definitiontype; accessing, via an instance of the software object type and theAPI, said target node from said source node through both the general SPIand the format specific SPI, based on the definition of the linkproperty definition type; and managing content in the plurality ofcontent repositories based upon the VCR.